The present invention relates to a wear-resistance aluminum bronze alloy which is suitable for use of a sliding member of a rolling mill, machine tool, apparatuses for ships as well as apparatuses for automobiles.
As sliding member comprising an aluminum bronze alloy to be used for the above use, an aluminum bronze of Cu-Al-Fe alloy, Cu-Al-Fe-Ni alloy or Cu-Al-Fe-Ni-Mn alloy in which to copper containing not more than 15 wt % of aluminum were added iron, iron and nickel, or iron, nickel and manganese, respectively, has heretofore been used in many cases.
The following copper alloys have conventionally been proposed.
Japanese Patent Publication No. 44-28789 (1969) discloses a wear-resistance copper alloy having improved wear-resistance and mechanical strength so as to be usable under high-speed and high-load conditions, produced by adding not more than 1.0 wt % in total of at least one selected from the group consisting of Cr, Ti, V and Zr to an alloy containing 55 to 67 wt % of Cu, 1.0 to 6.0 wt % of Mn, 0.1 to 1.2 wt % of Si, 0.1 to 6 wt % of Al, 0.1 to 3.0 wt % of Pb and the balance Zn.
Japanese Patent Application Laid-Open (KOKAI) No. 49-66527 (1974) discloses a wear-resistance copper alloy having improved wear-resistance at a high temperature, produced by adding not more than 10 wt % in total of at least one selected from the group consisting of Mn, Cr, Bi to an alloy containing 60 to 85 wt % of Cu, 6 to 13 wt % of Al, 3 to 20 wt % of Ni, 1 to 10 wt % of Co as the main ingredients.
Japanese Patent Publication No. 50-7010 (1975) discloses a copper alloy for a valve seat with excellent anti-seizing property and wear-resistance at a high temperature, comprising 25 to 40 wt % of Zn, 1 to 8 wt % of Al, 1 to 5 wt % of Mg, 0.3 to 2 wt % of Si, 0.8 to 3 wt % of Cr, 0.3 to 1 wt % of P, not more than 5 wt % of impurity elements and the balance Cu.
Japanese Patent Application Laid-Open (KOKAI) No. 51-133127 (1976) discloses a wear-resistance aluminum bronze for sliding member having excellent adhesive wear-resistance and anti-seizing property, characterized in that the amount of iron silicate dispersed in the Cu-Al alloy is not smaller than the eutectic composition in the quasibinary phase diagram of a Cu-Al phase and an iron silicate phase.
Japanese Patent Publication No. 52-50724 (1977) discloses an age-hardening copper alloy for a bearing or a clock, which comprises 5 to 35 wt % of Zn, 1 to 20 wt % of Ni, more than 1 wt % to not more than 8 wt % of Al and the balance substantially Cu, wherein an intermetallic compound of Ni, and Al is mainly separated out by heat-treatment.
Japanese Patent Application Laid-Open (KOKAI) No. 63-157825 (1988) discloses a wear-resistance alloy comprising 10 to 40 wt % of Zn, 3 to 10 wt % of Al, 0.1 to 4 wt % of Cr and the balance Cu.
Japanese Patent Publication No. 7-3943 (1933) discloses an alloy having magnetic property, excellent tensile strength and hardness as well as abrasion resistance and corrosion resistance, which comprises 40 to 85 wt % of Cu, 1 to 50 wt % of Fe, 0.1 to 35 wt % of Ni, 0.1 to 5 wt % of Cr and 0.1 to 7 wt % of Al.
Japanese Patent Application Laid-Open (KOKAI) No. 48-66525 (1973) discloses a copper alloy having wear-resistance at high temperature, which comprises 25 to 55 wt % of Fe, 2 to 8 wt % of Al, 1 to 10 wt % of Cr, 1 to 10 wt % of Ni and the balance Cu.
As an aluminum bronze alloy for a sliding member, a high-strength aluminum bronze alloys regulated by JIS H 5114 No. 3, which comprises not less than 78 wt % of Cu, 3.0 to 6.0 wt % of Fe, 8.5 to 10.5 wt % of Al, 3.0 to 6.0 wt % of Ni, not more than 1.5 wt % of Mn and not more than 0.5 wt % of impurity elements, which corresponds to ASTM B148 C 95800, the composition comprising not less than 78 wt % of Cu, 3.5 to 4.5 wt % of Fe, 8.5 to 9.5 wt % of Al, 4.0 to 5.0 wt % of Ni, 0.8 to 1.5 wt % of Mn, not more than 0.02 wt % of Si and not more than 0.05 wt % of Pb; and by JIS H 5114 No. 4, which comprises not less than 71 wt % of Cu, 2.0 to 5.0 wt % of Fe, 6.0 to 9.0 wt % of Al, 1.0 to 4.0 wt % of Ni, 7.0 to 15.0 wt % of Mn and not more than 0.5 wt % of impurity elements, which corresponds to ASTM B 148 C 95700, the composition comprising not less than 71.0 wt % of Cu, 2.0 to 4.0 wt % of Fe, 7.0 to 8.5 wt % of Al, 1.5 to 3.0 wt % of Ni, 11.0 to 14.0 wt % of Mn, not more than 0.03 wt % of Pb and not more than 0.10 wt % of Si.
When aluminum bronze is used as a sliding member, it is necessary to use it usually by supplying a lubricating oil composition such as grease, oil, etc. In using under the conditions of high temperature or in water at which the lubricating oil composition cannot be used, it is also necessary to use it by laying or coating a solid lubricating agent such as graphite, molybdenum disulfide, etc. at the sliding surface.
That is, a sliding member comprising aluminum bronze has advantages that it is (1) excellent in corrosion resistance and (2) excellent in mechanical strength, and (3) can be improved in its mechanical characteristics by quenching and annealing treatments, etc., since structural transformation is possible due to heat-treatment. To the contrary, it has disadvantage in friction wear characteristics, particularly, cohesive wear is likely caused so that it is inferior in anti-seizing property and involves the problem that remarkable decrease in wear-resistance is caused during usage under the conditions of low-speed and high-load for a long period of time.
Further, although these aluminum bronzes have characteristic of excellent in corrosion resistance, when these aluminum bronzes are, for example, used in sea water, there involve the problem that rapid decrease in corrosion resistance is cause with increase of iron in the compositional range of the aluminum bronzes containing less amount of nickel as compared with that of iron.
As a result of the present inventors' studies to solve the above-mentioned problems, it has been found that by adding chromium in place of iron in the composition of the conventional aluminum bronze, i.e. a wear-resistance aluminum bronze comprising 4 to 15 wt % of Al, 0.1 to 10 wt % of Cr and the balance Cu, and a wear-resistance aluminum bronze in which to the above composition is/are added not more than 6 wt % of nickel, or not more than 6 wt % of nickel and not more than 15 wt % of Mn, can be improved in sliding characteristics such as adhesive wear-resistance and anti-seizing property, and also exhibit excellent corrosion resistance during usage in sea water. The present invention has been achieved on the basis of this finding.